FIG. 3 illustrates an IC chip package according to China Pat. No. 01200427.8 issued on Oct. 31, 2001. The IC chip package is constructed to include a substrate 10, a chip 12, a cover 13, and adhesive means 14. The substrate 10 includes a top side 101 and a receiving chamber 102. The receiving chamber 102 has an opening at the top side 101. The top side 101 is provided with a plurality of connecting pads arranged around the opening of the receiving chamber 102. The substrate 10 further includes a plurality of plated through holes 103 provided around a periphery thereof, in order to electrically connect the connecting pads at the top of the substrate 10 to a bottom of the substrate 10. The chip 12 is fixedly mounted in the receiving chamber 102. The chip 12 is provided with a plurality of connecting pads respectively electrically connected to the connecting pads of the substrate 10 by means of bonding wires 15. The adhesive means 14 is applied on areas where the bonding wires 15 connect with the connecting pads of the substrate 10. The cover 13 is fixedly fastened to the adhesive means 14, thereby covering the opening of the receiving chamber 102. When the IC chip package is installed on a circuit board, tin solder is applied to bottoms of the through holes 103. The chip 12 is thereby electrically connected to a conductive circuit pattern of the circuit board.
In this IC chip package, it is generally difficult to control the amount of the adhesive means 14 applied. If insufficient adhesive means 14 is used, the cover 13 may not properly adhere to the substrate 10. Over time, tiny gaps may form between the cover 13 and the top side 101 of the substrate 10. If this happens, moisture may penetrate inside the receiving chamber 102 and adversely affect the functioning of the chip 12. In addition, the cover 13 may become detached from the substrate 10, which frequently causes complete failure of the IC chip package. On the other hand, if excessive adhesive means 14 is used, the adhesive means 14 is liable to overflow down along the through holes 103 to the bottom of the substrate 10. If this happens, the adhesive means 14 may form insulating coatings on the bottoms of the through holes 103, which frequently results in the substrate 10 being unable to properly electrically connect with the circuit board. Either way, the quality and/or reliability of the IC chip package is liable to be reduced.
Furthermore, the through holes 103 are exposed to ambient air, and are liable to be affected by oxidation or contamination. This can lead to faulty electrical connection of the substrate 10 with the circuit board.
What is needed, therefore, is an IC chip package with isolated vias having high quality and reliability.